For years, African militias have used proceeds from precious natural resources to fund conflicts – a practice dramatized in the 2006 Hollywood film "Blood Diamond." Now, there's a new twist: blood cows.

Warring rebel groups in the Democratic Republic of Congo are stealing and selling livestock to finance a conflict sparked by spillover from the 1994 Rwandan genocide, in which 800,000 were killed.

Vast and volatile, the Democratic Republic of Congo has long suffered from conflicts fought over its reserves of gold, copper, uranium, and coltan, a mineral needed in cellphones and other electronics. For years, armed groups have sought control over mines and forests, their acquisitions of wealth fueling cycles of violence. Cattle may sound less glamorous than precious metals, but they're accessible.

"It's just like the mining resources," says Alpha Sow, head of the local office of the United Nations Mission in Congo (MONUC). "Part of this money goes to buy munitions."

In January, the Congolese Army and two major rebel factions agreed to a cease-fire and opened peace talks. As MONUC redeployed to help pave the way for peace, both factions moved quickly to establish or strengthen their grip on territories across North Kivu province. Fighting resumed and cattle thievery soared.

"They came en masse. They stole night and day," farmer Gervais Ruhubika says, referring to the most notorious cattle thieves – a mostly Hutu militia known as PARECO (Coalition of Congolese Patriotic Resistance). He and his partners, who have a small farm in army-controlled territory outside Goma, saw their herd dwindle from 200 to 120. To make matters worse, Congolese soldiers also claimed a stake in the cows.

"Every morning," he says, "they came and demanded almost all the milk."

In the past year, the price of beef has doubled, fueled in part by the black-market trade in cattle. "PARECO has stolen all of the cows," says Antoine Nzovu, a manager at a slaughterhouse on the shores of Lake Kivu. "The thieves go with the cows to Walikale," a market in rebel-controlled territory to the west.

While the trade in blood cows finances rebel activity here, but it's also a form of psychological warfare. Another major rebel group in the region, the National Congress for the Defense of the People (CNDP), is a predominantly Tutsi movement which sees itself as protecting its people. It also defends their traditional livelihood; For centuries, the pastoral Tutsi have measured a man's wealth by counting his cattle.

"Nothing riles the CNDP and the Tutsi more than having their cattle stolen," says Anneke Van Woudenberg, senior Africa researcher at Human Rights Watch. When they turn to battle, she says, the CNDP can be brutal: In a bid to regain villages controlled by Hutu militias, in April the CNDP killed over 100 civilians, some of them the elderly and children.

The current wave of cattle-rustling has its roots in the Rwandan genocide, when an estimated million refugees, many of them Hutu participants in the genocide, fled across the border to eastern Congo. Hungry and landless, they obliterated the abundant cattle population of North Kivu.

"I lost 7,000 head of cattle in two weeks' time," says Kasuku wa Ngeyu, a prominent businessman and president of the cattle ranchers' association in North Kivu, which borders Rwanda.

Several years later, ranchers began replenishing their herds with cows purchased in Rwanda and Uganda. Mr. Wa Ngeyu says there are 180,000 cows in North Kivu today. But renewed fighting between the PARECO militia, closely aligned with Hutu leaders wanted in connection with the 1994 genocide, and CNDP, has threatened the progress the farmers have made. "It's still a war between the Hutus and the Tutsis," says Nicole Merlo, a rancher with 800 cows.